Provide the National Institute of Arthritis, Metabolism, and Digestive Diseases with 100 mgs of guinea pig insulin. Specifically, extract and purify 100 mgs of guinea pig insulin with the methods that have been established in his laboratory and widely published. Pancreata from guinea pigs will be extracted with acid ethanol, crude insulin removed by precipitation at pH7 and further purified by precipitation by ethanol-ether, gel filtration on Sephadex G-50, chromatography on an ion exchange column, and precipitation by puric acid.